Pentacoordinated chlorosilanes with C,O-chelate ligands derived from N-methyl-N’-organosulfonyl-prolinamides

Article abstract of DOI:10.1007/s10593-012-0949-7

The reaction of amides RSO₂-Pro-NHMe with ClCH₂SiMe₂Cl in the presence of (Me₃Si)₂NH gave pentacoordinatedchlorosilanes RSO₂-Pro-N(Me)CH₂SiMe₂Cl with an organosulfonyl group (R = Me, Ph, 4-ClC₆H₄, 4-BrC₆H₄, 4-MeC₆H₄, and 4-O₂NC₆H₄) attached to the proline nitrogen atom. An alternative method for the preparation of these compounds comprises the cyclosilylmethylation of proline methylamide by dimethylchloromethylchlorosilane to give the previously unreported heterocyclic 2-sila-5-piperazinone system in the first step. The bicyclic silacyclane synthesized is 2-sila-5-piperazinone condensed with a proline residue. The action of sulfonyl chlorides RSO₂Cl leads to cleavage of the sila ring Si–N bond to give the desired chlorosilanes. The hydrolysis of these products, depending on the reaction conditions, gives either silyloxonium chlorides [RSO₂-Pro-N(Me)CH₂SiMe₂OH₂]Cl or disiloxanes [RSO₂-Pro-N(Me)CH₂SiMe₂]₂O. X-ray diffraction structural analysis showed that the silicon atom in the chlorides and silyloxonium chlorides is pentacoordinated due to an intramolecular O→Si bond and has distorted trigonal-bipyrimidal configuration.²⁹Si NMR spectroscopy showed that the disiloxanes and bicyclic sila-5-piperazinone have a tetracoordinated silicon atom.

Full text of DOI:10.1007/s10593-012-0949-7

Chemistry of Heterocyclic Compounds, Vol. 47, No. 12, March, 2012 (Russian Original Vol. 47, No. 12, December, 2011)
PENTACOORDINATED CHLOROSILANES
WITH C,O-CHELATE LIGANDS DERIVED
FROM N-METHYL-N'-ORGANOSULFONYL-
PROLINAMIDES*
A. A. Nikolin1, D. E. Arkhipov2, A. G. Shipov1, E. P. Kramarova1,
N. A. Koval'chuk2, A. A. Korlyukov2**, V. V. Negrebetsky1, Yu. I. Baukov 1**,
A. R. Bassindale3, P. G. Taylor3, A. Bowden3, and S. Yu. Bylikin1,3
The reaction of amides RSO2-Pro-NHMe with ClCH2SiMe2Cl in the presence of (Me3Si)2NH gave
pentacoordinated chlorosilanes RSO2-Pro-N(Me)CH2SiMe2Cl with an organosulfonyl group (R = Me,
Ph, 4-ClC6H4, 4-BrC6H4, 4-MeC6H4, and 4-O2NC6H4) attached to the proline nitrogen atom. An
alternative method for the preparation of these compounds comprises the cyclosilylmethylation of
proline methylamide by dimethylchloromethylchlorosilane to give the previously unreported
heterocyclic 2-sila-5-piperazinone system in the first step. The bicyclic silacyclane synthesized is 2-sila-
5-piperazinone condensed with a proline residue. The action of sulfonyl chlorides RSO2Cl leads to
cleavage of the sila ring Si–N bond to give the desired chlorosilanes. The hydrolysis of these products,
depending on the reaction conditions, gives either silyloxonium chlorides [RSO2-Pro-
N(Me)CH2SiMe2OH2]Cl or disiloxanes [RSO2-Pro-N(Me)CH2SiMe2]2O. X-ray diffraction structural
analysis showed that the silicon atom in the chlorides and silyloxonium chlorides is pentacoordinated
due to an intramolecular O→Si bond and has distorted trigonal-bipyrimidal configuration. 29Si NMR
spectroscopy showed that the disiloxanes and bicyclic sila-5-piperazinone have a tetracoordinated
silicon atom.
Keywords: silacyclanes, pentacoordinated silicon compounds, X-ray structural analysis, synthesis.
_______
*Dedicated to the shining memory of our friend, Edmunds Lukevics, whom we knew, appreciated, and loved, a
bright, energetic, multifaceted personality, a scientist with a capital S, brilliant leader, highly erudite chemist,
who made a definitive contribution to the creation and development of a new area in silicon chemistry, namely,
silicon bioorganic chemistry.
**To whom correspondence should be addressed, e-mail: alex@xrlab.ineos.ac.ru, baukov@rgmu.ru.
1Russian State Medical University, 1 Ostrovityanova St, Moscow 117997, Russia.
2A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 Vavilova
St. , Moscow 119991, Russia.
3Open University, Walton Hall, Milton Keynes, MK7 6AA, Great Britain; e-mail: a.bassindale@open.ac.uk.
__________________________________________________________________________________________
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 12, pp. 1869-1890, December, 2011.
Original article submitted June 28, 2011.
0009-3122/12/4712-1565©2012 Springer Science+Business Media, Inc.
1565

Pentacoordinated C,O-chelates containing amidomethyl and related bidentate monoanionic ligands
(LCH2), which are typical representatives of silicon compounds with nonstandard coordination, have been
classified as hypercoordination complexes. Such complexes have been studied rather extensively [1-4]. The
strength of the intramolecular O→Si coordination bond in these compounds varies in a rather broad range
depending on the nature of the monodentate ligands at the silicon atom and substituents in the five-membered
chelate ring [1-11]. Investigation of the structure features of pentacoordinated C,O-chelates with the SiC3OX
coordination unit (X = Hal, OAlk, OAr, ½O, and Otf) [5, 10, 12-17] allows using these compounds as models
for studying hypervalence problem [1, 18, 19] and modeling pathways for SN reactions at the silicon atom
[1-5, 7-10, 20, 21].
Chlorosilanes, especially monochlorosilanes of LCH2SiMe2Cl type occupy an important place among
C,O-chelate complexes. Rather efficient methods have been developed for the preparation of such
monochlorosilanes [2, 12-17]. Furthermore, the synthesis of other derivatives of pentacoordinated silicon is
carried out starting from monochlorosilanes. At present, the Cambridge Crystallographic Data Center [22] has
information on about 50 neutral and ionic pentacoordinated C,O-mono- and bichelate silicon complexes with
amidomethyl and related ligands, 20 of which are chlorosilanes.
Nevertheless, we should note that no C,O-chelates with amino acid fragments within the substituent at
the amide carbon atom have been reported among the various types of pentacoordinated chlorosilanes known up
to date. In the present communication, data are given on the synthesis and chemical properties of
pentacoordinated chlorosilanes RSO2-Pro-N(Me)CH2SiMe2Cl with an organosulfonyl group attached to the
proline nitrogen atom as well as X-ray structural analysis data for these compounds. The products of the partial
hydrolysis of these proline derivatives, namely silyloxonium chlorides [RSO2-Pro-N(Me)CH2SiMe2OH2]Cl are
also reported.
We have used the direct N-dimethylchlorosilylmethylation of amides and lactams by the ClCH2SiMe2Cl–
(Me3Si)2NH system under thermodynamic control conditions for the synthesis of the desired N-methyl-N-(di-
methylchlorosilylmethyl)-N'-organosulfonylprolinamides [17]. Such reactions with 2-amino acid derivatives,
with the exception of 2,5-piperazinedione [23], have not yet been examined.
O
Me
O
ClCH2SiMe2Cl, (Me3Si)2NH
– Me3SiCl, – NH4Cl
Si
N
Cl
Me
N
N
NHMe
SO2R
SO2R
Me
2a,f, (S)-2b–e
1a,f, (S)-1b–e
a R = Me, b R = Ph, c R = 4-MeC6H4, d R = 4-ClC6H4, e R = 4-BrC6H4, f R = 4-O2NC6H4
IR monitoring of the course of N-methyl-N'-(organosulfonyl)prolinamides 1a-f reactions with
ClCH2SiMe2Cl in the presence of (Me3Si)2NH showed that the reaction of these compounds upon refluxing in
benzene or toluene for 7-14 h when the ratio of the amide and ClCH2SiMe2Cl was 1:1 leads to the formation of a
mixture of starting amide 1 ((NCO) ~ 1680 cm-1) and chloride 2 ((NCO) ~ 1605 cm-1). Chlorosilanes 2a-f were
isolated preparatively using an amide to ClCH2SiMe2Cl ratio equal to 1:2. The reaction of methylamide (S)-1c
with ClCH2SiMe2Cl was also carried out in the presence of Et3N according to Hillyard et al. [13]. IR spectral
monitoring of the course of this reaction showed that it proceeds over 3 h in benzene at reflux with the
methylamide to ClCH2SiMe2Cl ratio equal to 1:1. However, the yield of compound (S)-2c was lower than when
the ClCH2SiMe2Cl–(Me3Si)2NH system was used. Retention of configuration in the case of enantiomers of
proline derivatives was confirmed by X-ray structural analysis of the monocrystals.
The composition and structure of hygroscopic chlorosilanes 2, which are readily hydrolyzed even upon
1
brief contact with the air, were established by elemental analysis (except compounds (S)-2b and (S)-2f), IR H,
13C, and 29Si NMR spectroscopy (for compound (S)-2c), and X-ray structural analysis.
1566

The low-frequency shift of the absorption band corresponding to the NCO fragment in the IR spectra of
chlorosilanes 2 (to ~1605 cm-1) relative to starting methylamides 1 and the presence of a second, less intense
absorption band at ~1510 cm-1 indicate the (O→Si)-chelate structure of chlorosilanes 2 [15].
We have proposed still another pathway to C,O-chelates of type 2 realized for (S)-proline methylamide
((S)-3), which, in contrast to prolinamides 1, have a free proline NH group. The silylmethylation of amide (S)-3
by the ClCH2SiMe2Cl–(Me3Si)2NH system or its treatment with ClCH2SiMe2Cl in the presence of Et3N led to
previously unreported bicyclic silacyclane (S)-4. We may assume that the product of N-dimethylchloro-
silylmethylation at the amide nitrogen atom, chlorosilane A (or/and its N'-TMS derivative using hexamethyl-
disilazane) is initially formed in these reactions and then undergoes thermal decomposition with the loss of HCl
(respectively, Me3SiCl) during fractionation, leading to the desired silacyclane (S)-4.
ClCH2SiMe2Cl,
(Me3Si)2NH
HN
– MeSiCl,
– NH4Cl
N
Me
Me
Si
O
Me
N
O
N
– HCl
O
N
ClCH2SiMe2Cl,
Et3N
– Et3N.HCl
H
NHMe
Si
Me
(S)-4
Me
Me
(S)-3
Cl
A
RSO2Cl
(S)-2b,c
The IR spectrum of silacyclane (S)-4 features a stretching vibrational band for the NCO group at
~1640 cm-1, while its 29Si NMR spectrum shows a silicon chemical shift (~4 ppm) typical for the tetracoordi-
nated silicon atom in a comparable environment [4, 24-26].
The subsequent reaction of silacyclane (S)-4 with sulfonyl chlorides led to (O→Si)-chelate
chlorosilanes (S)-2b,c in yields comparable to those for previously prepared derivatives 2.
We have already noted the high tendency of chlorosilanes 2 to undergo hydrolysis, which is markedly
greater than for previously reported C,O-chelate pentacoordinated chlorosilanes [15, 28]. Thus, recrystallization
in the air led to the formation of silyloxonium chlorides [RSO2-Pro-N(Me)CH2SiMe2OH2]Cl 5a-f. The general
sequence of transformations presented below has been proposed for describing the formation of various
compounds in the hydrolysis of pentacoordinated C,O-chelate chlorosilanes A' on the basis of the structures
established for the intermediate and final hydrolysis products [25, 28].
The first step of hydrolysis is the formation of a silyloxonium chloride (silanol hydrochloride) B, which
loses water to give protonated disiloxane C. The loss of HCl (generally occurring upon the addition of an HCl
acceptor) leads to the conversion of protonated disiloxane C into disiloxane D.
Some time after dissolving chlorosilanes 2 in CDCl3, the 1H NMR spectrum of this solution shows a broad
13
signal at 6-8 ppm, which we assigned to the –OH2+ group. The C=O group signal in the C NMR spectra of these
compounds at 170-172 ppm is much broadened, which makes its precise observation impossible in most cases.
Z
Z
Cl–
HO
Me
Me
Me
Si
Me
Me
Me
N
O
O
Si
O
– H2O
N
OH
Me
– 2HCl
+ 2HCl
2H2O
O
+
Me
Si
O+
N
Z
Z
N
Si
+ H2O
Me
Cl–
H
Me
C
Me
Me
D
Cl
2
2
H
A'
B
Z = N-(organosulphonyl)proline residue
1567

29
Taking account of the upfield position of the signal in the Si NMR spectrum (from -33 to -36 ppm), this data,
in our opinion, indicate the formation of the products of the first step in the hydrolysis of chlorosilanes 2,
namely, silyloxonium chlorides 5, under these conditions.
Me
H
N
O+
H2O
2a,f, (S)-2b–e
N
S
H
Si
O
Me
O
O
Me
Cl
R
5a,f, (S)-5b–e
The chemical shift of the signal in the 29Si NMR spectra (from -33 to -36 ppm, in CDCl3) indicates a
pentacoordinated state for silicon in solutions of chlorosilanes 2, which corresponds to the shift for C,O-chelate
pentacoordinated monochlorosilanes with similar structure [4, 26]. We have found using the 29Si NMR CP/MAS
method for complexes 5a, 5f, and (S)-5c that silyloxonium chlorides 5 in the solid phase, as should have been
expected, have an even stronger upfield silicon signal shift (-40.2, -42.2, and -43.4, respectively).
We established the nature of the O→Si coordination interaction in silyloxonium chlorides 5 in solution
on the basis of the "coordination contribution" values, which permit to evaluate this interaction by using the
difference in the chemical shifts between the pentacoordinated complex and a model compound containing a
tetracoordinated silicon atom: - = Si(V) - Si(IV) [4, 26, 27]. Me3SiCl (Si(IV) 29.9 ppm) was taken as the
model compound. Comparison of the calculated values of - for complexes 5a, (S)-5b-e, and 5f (62.7, 63.4,
63.9, 62.9, 65.9, and 66.7 ppm, respectively) with the analogous values for C,O-chelate N-(monochlorosilyl-
methyl)amides with a pentacoordinated silicon atom (65-75 ppm) [4, 27] indicates realization of an O→Si
coordination interaction in solutions of silyloxonium chlorides 5. The extent of this coordination interaction is
similar to that in the case of the above-mentioned neutral C,O-chelate silylmethyl amide derivatives of type A.
The products of the final step of these transformations, namely, disilyloxanes 6, were obtained by the
hydrolysis of monochlorosilanes 2 in the presence of NaHCO3 as a base.
H2O, NaHCO3
[RSO2-Pro-N(Me)CH2SiMe2]2O
RSO2-Pro-N(Me)CH2SiMe2Cl
6a,f, (S,S)-6b–e
2a,f, (S)-2b–e
The composition and structure of the obtained disiloxanes 6a-f were established using elemental
1
13
29
analysis (except for (S,S)-6b and 6f) and H, C, and Si NMR spectroscopy as well as infrared spectroscopy.
The IR spectra of disiloxanes 6 showed a strong absorption band for the free amide group at 1650 cm-1. The
signal of the tetracoordinated silicon atom in the 29Si NMR spectra appeared in the narrow region (4-5 ppm)
characteristic for disiloxanes [4, 29].
We have found that disiloxanes 6 readily react with electrophilic agents. For example, the reaction of
compounds (S,S)-6c and 6f with SOCl2 proceeds readily even at room temperature and leads to the formation of
chlorosilanes (S)-2c and 2f, respectively, in high yield. The synthesis of these chlorosilans by other means was
described above.
The structures of chlorosilanes 2a-f and silyloxonium chlorides 5a,c,d,f were established by X-ray
structural analysis. The silicon atom in all these structures has distorted trigonal-bipyramidal (TBP) geometry.
The deviation of the silicon atom from the plane of the equatorial atoms is in the range 0.01-0.08 Å (Tables 1
and 2, Figs. 1-10). Thus, in the framework of the structural correlation method, the geometry of the silicon atom
coordination unit corresponds to a transition state of SN2 reactions at a tetrahedral silicon atom.
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1569

In the framework of this approach, atom O(1) is considered as a nucleophile, while the exocyclic
substituent (X = OH2, Cl) is considered as a leaving group. The difference between the standard values of the
Si–O (1.64 Å) and Si–Cl (2.07 Å) bond lengths [30] and the experimental values for compounds 2a-f and
5a,c,d,f, i.e., the relative lengthening of the bonds, is 0.23-0.31 Å (X = OH2) and 0.20-0.29 Å (X = Cl). In turn,
the length of the Si(1)–O(1) coordination bond varies in the range 1.91-2.01 Å. Analysis of the Si(1)–O(1)
bonds lengths in chlorosilanes 2a-f indicates the absence of a direct relationship between the lengths of these
bonds and the electron-withdrawing (inductive) effect of the N-organosulfonylproline substituent. The shortest
Si–O bond is found for compound 2a, while the longest Si–O bond is found for (S)-2b. Weak intermolecular
interactions in the crystal also apparently have a significant effect on this bond length in addition to the
inductive effect in the structures of chlorosilanes 2a-f.
Fig. 1. General view of complex 2a. The atoms are represented by 50%-probability thermal vibration ellipsoids.
The hydrogen atoms are not shown.
Fig. 2. General view of complex (S)-2b. The atoms are represented by 50%-probability thermal vibration
ellipsoids. The hydrogen atoms are not shown.
1570

Fig. 3. General view of complex (S)-2c. The atoms are represented by 50%-probability thermal vibration
ellipsoids. The hydrogen atoms are not shown.
Fig. 4. General view of complex (S)-2d. The atoms are represented by 50%-probability thermal vibration
ellipsoids. The hydrogen atoms are not shown.
Fig. 5. General view of complex (S)-2e. The atoms are represented by 50%-probability thermal vibration
ellipsoids. The hydrogen atoms are not shown.
1571

Fig. 6. General view of complex 2f. The atoms are represented by 50%-probability thermal vibration ellipsoids.
The hydrogen atoms are not shown.
Fig. 7. General view of complex 5a. The atoms are represented by 50%-probability thermal vibration ellipsoids.
Only the hydrogen atoms of the oxonium fragment are shown.
Fig. 8. General view of complex (S)-5c. The atoms are represented by 50%-probability thermal vibration
ellipsoids. Only the hydrogen atoms of the oxonium fragment are shown.
1572

Structures analogous to complexes 5a-d were discussed in our previous work [28] for two salts with the
(benzoylamido)methyl ligand. The lengths of the Si(1)–O(1) bonds in these salts are 0.03-0.08 Å greater than in
5a-d, while the Si(1)–O(1) bond length varies only slightly (by 0.01-0.03 Å). This latter finding can be
attributed to the effect of the crystal packing and observed differences in the hydrogen bond system. Indeed,
hydrogen-bonded dimers are observed in the structure of compound 5f, while a spiral along the crystallographic
65 axis is noted in the structure of compound (S)-5c due to O–H···Cl bonds. The interatomic O···Cl and H···Cl
distances are 2.83-3.06 and 2.00-2.21 Å, respectively.
Coordination polyhedra may be seen in the Holmes formalism [31] as points on the potential energy
surface of a hypothetical polytopic rearrangement. The silicon atom coordination polyhedron changes during the
rearrangement from ideal TBP to an ideal square pyramid (SP). The general scheme for evaluating the of
pseudorotation coordinate comprises 1) calculation of all the dihedral angles between the faces of the given
polyhedron (nine angles), 2) calculation of the difference between the corresponding angles of the given
polyhedron and the ideal TBP and SP polyhedron, 3) summation of the deviations for TBP and SP, and 4)
plotting a curve in coordinates of the deviation from TBP vs. (100 – deviation from SP).
Fig. 9. General view of complex (S)-5d. The atoms are represented by 50%-probability thermal vibration
ellipsoids. Only the hydrogen atoms of the oxonium fragment are shown.
Fig. 10. General view of complex 5f. The atoms are represented by 50%-probability thermal vibration
ellipsoids. Only the hydrogen atoms of the oxonium fragment are shown.
1573

TABLE 3. Deviations from TBP and SP for Complexes 2a-f, 5a,c,d,f
Polyhedron
Deviation from TBP, %
100 – deviation from SP, %
Δ, %
2a_1*
2a_2*
2b
15.10
13.38
14.32
10.21
12.22
12.06
14.38
10.98
18.23
10.15
13.25
14.89
11.74
7.75
0.20
1.64
6.57
0.31
5.44
5.06
5.37
3.12
0.00
0.00
0.16
2c
9.90
2d
6.79
2e
7.00
2f
9.01
5a
7.87
5c
18.23
10.15
13.09
5d
5f
_______
*Numbers 1 and 2 indicate two crystallographically independent silicon atoms.
A part of the pseudorotation trajectory may be described by examining a series of complexes with the
same coordination polyhedron. The deviation values from TBP and SP are given in Table 3. A direct
dependence of the deviations from TBP and SP is not observed for all the complexes studied. The difference ()
for chloride 2b reaches 6.57%. It should be noted that the silicon coordination polyhedra of silyl chlorides
(max 6.57%) deviate more significantly from the Berry coordinate than in the case of the corresponding
silyloxonium polyhedra (max 3.12%). The deviation of the silicon atom polyhedra from ideal TBP lies in a
rather narrow range (10-18%). Thus, complexes 2a,c, 5a,c,d,f with small  describe the initial step of a Berry
pseudorotation.
EXPERIMENTAL
The IR spectra were recorded in various solvents and in solid phase (using the incomplete internal
reflection modulus) on a Bruker Tensor-27 spectrometer. The 1H, 13C, and 29Si NMR spectra were recorded on a
Bruker Avance II 300 spectrometer at 300, 75, and 60 MHz, respectively and Bruker Avance II 600
spectrometer at 600, 151, and 119 MHz, respectively. Some of the 29Si NMR spectra were recorded on a
Jeol JNM-EX400 spectrometer at 80 MHz in a pulse mode using Fourier transformation, 2H-stabilization of the
resonance conditions, and TMS as internal standard. The 29Si NMR spectra were recorded using the
1H-29Si HSQC pulse sequence provided in the mathematical package for the Bruker Avance II 600 spectrometer
[32]. The 29Si CP/MAS spectra in the solid state were recorded on a Jeol JNM-EX400 spectrometer.
Starting N-tosyl-(S)-proline monohydrate ((S)-7c) [33], racemic N-(4-nitrophenylsulfonyl)proline (7f),
N-(4-chlorophenylsulfonyl)-(S)-proline ((S)-7d) [34], N-(4-bromophenylsulfonyl)-(S)-proline ((S)-7e) [35], and
(S)-proline N-methylamide ((S)-3) [36] were prepared by reported procedures. The physicochemical properties
of these proline derivatives corresponded to the literature data.
N-Mesylproline Ethyl Ester (7a). A mixture of proline hydrochloride (75.8 g, 0.5 mol), absolute
ethanol (200 ml), and Me3SiCl (140.0 g, 1.3 mol) was heated at reflux for 9 h. After cooling to room
temperature, the lower layer was separated and evaporated in vacuum. The residue was mixed with ice water
(20 ml) and ether (100 ml). A solution of KOH (28.0 g, 0.5 mol) in water (20 ml) was added over 5 min with
stirring and ice cooling followed by calcinated K2CO3 (250 g) until a thick, difficult to stir mass formed in the
bottom layer. The ethereal layer was separated and the thick mass was washed with ether (2×50 ml). The
combined ethereal layers were dried with calcinated MgSO4. Ether was removed in vacuum and
1574

1575

the residue was fractionated. Yield 50.0 g (70%); bp 78-80ºС (13 mm Hg) (lit. bp 82-83ºС (17 mm Hg) [38]).
nD 1.4484. Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 1.15 (3H, t, 3J = 7.3, CH2СН3); 1.58-1.81 and 1.96-2.10
(4H, m, 3,4-СH2); 2.40 (1H, br. s, NH); 2.75–2.85 and 2.95–3.05 (2H, m, 5-СH2); 3.39–3.58 (1H, m, 2-CH); 4.10
(2H, q, 3J = 7.3, CH2СН3).
20
1
MeSO2Cl (5.73 g, 50 mmol) was added dropwise with stirring and cooling to a mixture of the prepared
proline ethyl ester (7.15 g, 50 mmol) and Et3N (5.05 g, 50 mmol) in ether (40 ml). The mixture was stirred for 2
h. The precipitate formed was filtered off and washed with 15 ml ether. The filtrate was evaporated in vacuum.
Fractionation of the residue gave 8.30 g (72%) compound 7a. Bp 176-177°С (9 mm Hg); mp 31-32°С. IR
spectrum (CHCl3), , сm–1: 1745 (C=O), 1360 and 1160 (SO2). 1Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 1.25
3
(3H, t, J = 7.3, CH2СН3); 1.85–2.11 and 2.14-2.37 (4H, m, 3,4-СH2); 2.98 (3Н, s, СН3S); 3.31-3.61 (2H, m,
3
5-СH2); 4.16 (2H, q, J = 7.3, CH2СН3); 4.37-4.51 (1H, m, 2-CH). 13С NMR spectrum (СDCl3), δ, ppm: 8.9
(СН2СН3); 19.4 (C-4); 25.7 (C-3); 32.7 (СН3S); 43.0 (C-5); 55.3 (СН2СН3); 56.2 (C-2); 173.8 (C=O). Found, %:
C 43.41; H 6.98; N 6.31. C8H15NO4S. Calculated, %: С 43.42; Н 6.83; N 6.33.
N-Phenylsulfonyl-(S)-proline Ethyl Ester ((S)-7b). PhSO2Cl (8.83 g, 50 mmol) was added dropwise
with stirring and cooling with water to (S)-proline ethyl ester (7.15 g, 50 mmol) and Et3N (5.05 g, 50 mmol) in
ether (40 ml). The reaction mixture was stirred for 2 h. The precipitate formed was filtered off and washed with
ether (15 ml). The filtrate was evaporated in vacuum and the oily residue was crystallized by trituration in
heptane. Yield 12.56 g (89%); mp 53-55°С. [α]D -87.0° (c 3.0, CHCl3). IR spectrum (CHCl3), , сm–1: 1750
25
(C=O), 1590 (Ph), 1360 and 1160 (SO2). 1Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 1.24 (3H, t, 3J = 7.3, CH2СН3);
1.60-2.17 (4H, m, 3,4-СH2); 3.25–3.55 (2H, m, 5-СH2); 4.11-4.20 (2H, m, CH2СН3); 4.25-4.44 (1H, m, 2-CH);
7.45-7.67 (3H, m, H Ph); 7.87 (2H, d, 3J = 7.7, H Ph). 13С NMR spectrum (СDCl3), δ, ppm: 14.0 (CH2СН3); 24.5
(C-4); 30.8 (C-3); 48.3 (C-5); 60.4 (CH2СН3); 61.2 (C-2); 127.3 (C-3,5 Ph); 128.9 (C-2,6 Ph); 132.7 (C-1 Ph); 138.3
(C-4Ph); 171.9 (C=O). Found, %: C 55.23; H 6.08; N 5.01. C13H17NO4S. Calculated, %: С 55.11; Н 6.05; N 4.94.
N-Arylsulfonylproline Ethyl Esters 8c-f (General Method). Freshly distilled SOCl2 (23.8 g, 0.2 mol)
was added dropwise with vigorous stirring and cooling to -15°C to absolute ethanol (75 ml). Then, N-aryl-
sulfonylproline 7c-f (0.1 mol) was added in portions. The reaction mixture was slowly brought to reflux, heated
at reflux for 1.5 h, and cooled to 0°C. The crystalline precipitate was filtered off, recrystallized from aqueous
ethanol, and dried in the air.
N-Tosyl-(S)-proline Ethyl Ester ((S)-8c). Yield 25.3 g (85%); mp 98-99°С (EtOH), [α]D25 -93.1° (c 3.47,
1
CHCl3). IR spectrum (KBr), , сm–1: 1654 (s, C=O), 1600 (w, Ar), 1360 (s), 1160 (s, SO2). Н NMR spectrum
(CDCl3), δ, ppm (J, Hz): 1.27 (3H, t, 3J = 7.3, CH2СН3,); 1.67–2.14 (4H, m, 3,4-СH2); 2.43 (3Н, s, СН3); 3.24–3.39
and 3.41–3.57 (2H, m, 5-СH2); 4.08–4.24 (2H, m, CH2СН3); 4.25–4.35 (1H, m, 2-CH); 7.34 (2H, d, 3J = 8.3, H Ar);
7.75 (2H, d, 3J = 8.3, H Ar). 13С NMR spectrum (СDCl3), δ, ppm: 8.8 (CH2СН3); 16.3 (СН3C6H4); 19.4 (C-4); 25.7
(C-3); 43.1 (C-5); 55.3 (CH2СН3); 56.0 (C-2); 127.1 (C-3,5 Ar); 128.3 (C-2,6 Ar); 144.2 (C-1 Ar); 156.4 (C-4 Ar);
173.8 (C=O). Found, %: C 56.47; H 6.33; N 4.61. C14H19NO4S. Calculated, %: С 56.55; Н 6.44; N 4.71.
N-(4-Chlorophenylsulfonyl)-(S)-proline Ethyl Ester ((S)-8d). Yield 28.4 g (89%); mp 84-84.5°С
(EtOH), [α]D -96.9° (c 1.4, CHCl3). IR spectrum (KBr), , сm–1: 1751 and 1569 (NCO), 1585 (Ar), 1346 and
25
1
3
1162 (SO2). Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 1.23 (3H, t, J = 7.3, CH2СН3); 1.68–2.12 (4H, m,
3,4-СH2); 3.22-3.45 (2H, m, 5-СH2); 4.03-4.19 (2H, m, CH2СН3); 4.23–4.31 (1H, m, 2-CH); 7.45 (2H, d, 3J = 8.7,
3
13
H Ar); 7.78 (2H, d, J = 8.7, H Ar). С NMR spectrum (СDCl3), δ, ppm: 8.9 (CH2СН3); 19.4 (C-4); 25.7 (C-3);
43.0 (C-5); 55.3 (CH2СН3); 56.2 (C-2); 127.1 (C-3,5 Ar); 128.3 (C-2,6 Ar); 144.2 (C-1 Ar); 156.4 (C-4 Ar); 173.8
(C=O). Found, %: C 49.22; H 5.13; N 4.35; S 9.91. C13H16ClNO4S. Calculated, %: С 49.13; Н 5.07; N 4.41;
S 10.09.
N-(4-Bromophenylsulfonyl)-(S)-proline Ethyl Ester ((S)-8e). Yield 33.7 g (93%); mp 71-72°С
(EtOH), [α]D -69.5° (c 2.72, CHCl3). IR spectrum (KBr), , сm–1: 1753 (NCO), 1585 (Ar, NCO), 1346 and
25
1
3
1162 (SO2). Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 1.21 (3H, t, J = 7.3, CH2СН3); 1.68-2.18 (4H, m,
3,4-СH2); 3.25-3.51 (2H, m, 5-СH2); 4.03–4.19 (2H, m, CH2СН3); 4.23-4.31 (1H, m, 2-CH); 7.63 (2H, d, 3J = 8.7,
1576

H Ar); 7.73 (2H, d, 3J = 8.7, H Ar). 13С NMR spectrum (СDCl3), δ, ppm: 13.97 (CH2СН3); 24.5 (C-4); 30.8 (C-3);
48.2 (C-5); 60.4 (CH2СН3); 61.3 (C-2); 127.6 (C-4 Ar); 128.9 (C-3,5 Ar); 132.1 (C-2,6 Ar); 137.5 (C-1 Ar); 171.8
(C=O). Found, %: C 43.28; H 4.46; N 3.76; S 8.55. C13H16BrNO4S. Calculated, %: С 43.10; Н 4.45; N 3.87;
S 8.85.
N-(4-Nitrophenylsulfonyl)proline Ethyl Ester (8f). Yield 29.1 g (88%); mp 94-95°С (EtOH). IR
1
spectrum (CHCl3), , сm–1: 1747 (CO), 1600 (Ar), 1525 (NO2), 1360 (NO2, SO2), 1160 (SO2). Н NMR
3
spectrum (CDCl3), δ, ppm (J, Hz): 1.26 (3H, t, J = 7.3, CH2СН3); 1.80-2.32 (4H, m, 3,4-СH2); 3.46 (2H, t,
3J = 6.2, 5-СH2); 4.06-4.27 (2H, m, CH2СН3); 4.38–4.52 (1H, m, 2-CH); 8.08 (2H, d, 3J = 8.7, H Ar); 8.36 (2H,
d, 3J = 8.7, H Ar). 13С NMR spectrum (СDCl3), δ, ppm: 9.1 (CH2СН3); 24.3 (C-4); 28.9 (C-3); 48.9 (C-5); 59.4
(CH2СН3); 61.4 (C-2); 124.6 (C-3,5 Ar); 128.9 (C-2,6 Ar); 142.6 (C-1 Ar); 149.8 (C-4 Ar); 172.5 (C=O). Found,
%: C 47.49; H 4.35; N 8.60. C13H16N2O6S. Calculated, %: С 47.55; Н 4.19; N 8.53.
N'-(Arylsulfonyl)-N-methylprolinamides 1a-f (General Method). A mixture of N-arylsulfonyl-
proline ethyl ester 8a-f (30 mmol) and 40% aqueous MeNH2 (30 ml) was stirred at room temperature for seven
days. The precipitate formed was filtered off and dried in the air.
N'-Mesyl-N-methylprolinamide (1a). Yield 6.2 g (95%); mp 152-153°C (EtOH). IR spectrum
1
(CHCl3), , сm–1: 1670 and 1527 (NCO), 1360 and 1160 (SO2). Н NMR spectrum (CDCl3), δ, ppm (J, Hz):
3
1.81-2.20 and 2.22-2.49 (4H, m, 3,4-СH2); 2.83 (3H, d, J = 4.5, СН3N); 2.87 (3Н, s, СН3S); 3.29-3.42 and
3.44–3.63 (2H, m, 5-СH2); 4.08-4.24 (1H, m, 2-CH); 6.76 (1H, br. s, NH). 13С NMR spectrum (СDCl3), δ, ppm:
24.8 (C-4); 26.5 (СН3N); 30.8 (C-3); 34.6 (СН3S); 49.6 (C-5); 62.5 (C-2); 171.8 (C=O). Found, %: C 40.88;
H 6.81; N 13.50. C7H14N2O3S. Calculated, %: С 40.76; Н 6.84; N 13.58.
N-Methyl-N'-phenylsulfonyl-(S)-prolinamide ((S)-1b). Yield 6.6 g (82%); mp 130-131°C (EtOH),
[α]D25 -159.6° (c 2.8, CHCl3). IR spectrum (KBr), , сm–1: 1643 and 1570 (NCO), 1360 and 1160 (SO2). 1Н NMR
3
spectrum (CDCl3), δ, ppm (J, Hz): 1.46-1.67 and 2.10-2.20 (4H, m, 3,4-СH2); 2.84 (3H, d, J = 4.8, CH3N);
3.12-3.18 and 3.52-3.57 (2H, m, 5-СH2); 4.05-4.09 (1H, m, 2-CH); 6.92 (1H, br. s, NH); 7.55 (2H, t, 3J = 7.7, H Ar);
3
3
13
7.62 (1H, t, J = 7.7, H Ar); 7.67 (2H, d, J = 7.7, H Ar). С NMR spectrum (СDCl3), δ, ppm: 24.2 (C-4); 26.4
(СН3N); 29.9 (C-3); 49.8 (C-5); 62.6 (C-2); 127.7 (C-3,5 Ar); 129.3 (C-2,6 Ar); 133.4 (C-1 Ar); 135.6 (C-4 Ar);
171.6 (C=O). Found, %: C 53.49; H 6.02; N 10.33. C12H16N2O3S. Calculated, %: С 53.71; Н 6.01; N 10.44.
N-Methyl-N'-tosyl-(S)-prolinamide ((S)-1c). Yield 8.5 g (96%); mp 123-125°C (EtOAc–hexane, 1:5)
(lit. mp 122-124 C [39]), [α]D -168.6° (c 3.71, CHCl3). IR spectrum (KBr), , сm–1: 1697 (Ar), 1654 and 1531
25
(NCO), 1360, 1160 (SO2). 1Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 1.14–1.83 and 2.04-2.28 (4H, m, 3,4-СH2);
2.45 (3Н, s, СН3); 2.87 (3H, d, 3J = 5.2, СН3N); 3.07-3.26 and 3.47-3.66 (2H, m, 5-СH2); 4.01-4.13 (1H, m, 2-CH);
6.95 (1H, br. s, NH); 7.36 (2H, d, 3J = 8.3, H Ar); 7.72 (2H, d, 3J = 8.3, H Ar).
N'-(4-Chlorophenylsulfonyl)-N-methyl-(S)-prolinamide ((S)-1d). Yield 8.7 g (95%); mp 176-177°C
(EtOH), [α]D25 -157.4° (c 4.4, CHCl3). IR spectrum (KBr), , сm–1: 1651 and 1568 (NCO), 1360 and 1160 (SO2).
3
1Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 1.45-1.75 and 2.10-2.22 (4H, m, 3,4-СH2); 2.81 (3H, d, J = 4.9,
СН3N); 3.09-3.18 and 3.45-3.57 (2H, m, 5-СH2); 3.95-4.08 (1H, m, 2-CH); 6.80 (1H, br. s, NH); 7.48 (2H, d,
3J = 8.8, H Ar); 7.72 (2H, d, 3J = 8.8, H Ar). 13С NMR spectrum (СDCl3), δ, ppm: 19.1 (C-4); 21.4 (СН3N); 24.9
(C-3); 44.7 (C-5); 57.4 (C-2); 127.1 (C-3,5 Ar); 128.3 (C-2,6 Ar); 142.1 (C-1 Ar); 154.8 (C-4 Ar); 174.6 (C=O).
Found, %: C 47.50; H 4.98; N 9.30. C12H15ClN2O3S. Calculated, %: С 47.60; Н 4.99; N 9.25.
N'-(4-Bromophenylsulfonyl)-N-methyl-(S)-prolinamide ((S)-1e). Yield 9.9 g (95%); mp 151-153°C
(EtOH), [α]D25 -146.3° (c 4.3, CHCl3). IR spectrum (KBr), , сm–1: 1650 (s) and 1534 (m, NCO), 1600 (m, Ar),
1
1360 (s) and 1160 (s, SO2). Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 1.45-1.80 and 2.10-2.25 (4H, m,
3,4-СH2); 2.81 (3H, d, 3J = 4.9, СН3N); 3.05-3.21 and 3.45-3.61 (2H, m, 5-СH2); 3.95-4.08 (1H, m, 2-CH); 6.87
13
(1H, br. s, NH); 7.69 (4H, m, H Ar). С NMR spectrum (СDCl3), δ, ppm: 24.4 (C-4); 26.4 (СН3N); 30.2 (C-3);
50.1 (C-5); 62.8 (C-2); 128.8 (C-4 Ar); 129.3 (C-3,5 Ar); 132.8 (C-2,6 Ar); 134.8 (C-1 Ar); 171.4 (C=O). Found,
%:
C
41.60;
H
4.39;
N
8.15. C12H15BrN2O3S. Calculated, %:
С
41.51;
Н
4.35;
N
8.07.
1577

N-Methyl-N'-(4-nitrophenylsulfonyl)prolinamide (1f). Yield 8.7 g (92%); mp 172-174°C (EtOH). IR
1
spectrum (CHCl3), , сm–1: 1670 (NCO), 1600 (Ar), 1525 (NCO, NO2), 1360 (NO2, SO2), 1160 (SO2). Н NMR
3
spectrum (CDCl3), δ, ppm (J, Hz): 1.48-2.00 and 2.15-2.34 (4H, m, 3,4-СH2); 2.89 (3H, d, J = 4.9, СН3N);
3
3.09-3.28 and 3.53-3.72 (2H, m, 5-СH2); 4.04-4.18 (1H, m, 2-CH); 6.76 (1H, br. s, NH); 8.05 (2H, d, J = 8.7,
H Ar); 8.42 (2H, d, 3J = 8.7, H Ar). 13С NMR spectrum (СDCl3), δ, ppm: 24.3 (C-4); 26.5 (СН3N); 30.3 (C-3); 49.9
(C-5); 62.7 (C-2); 124.6 (C-3,5 Ar); 129.0 (C-2,6 Ar); 141.6 (C-1 Ar); 150.5 (C-4 Ar); 170.9 (C=O). Found, %:
C 46.03; H 4.80; N 13.42. C12H15N3O5S. Calculated, %: С 46.00; Н 4.83; N 13.41.
N'-Mesyl-N-(dimethylchlorosilylmethyl)-N-methylprolinamide (2a). A mixture of methylamide 1a
(2.17 g, 10 mmol), (Me3Si)2NH (1.61 g, 10 mmol) and Me2Si(Cl)CH2Cl (2.86 g, 20 mmol) in toluene (10 ml)
was heated at reflux for 4 h and filtered while hot. The filtrate was cooled to room temperature. The crystalline
precipitate was filtered off, washed with ether (5 ml), and dried. Yield 2.91 g (90%); mp 115-118°С (MeCN).
IR spectrum (KBr), , сm–1: 1607, 1508 (NCO), 1325 and 1143 (SO2). Found, %: C 38.44; H 6.99; N 8.69.
C10H21ClN2O3SSi. Calculated, %: С 38.39; Н 6.76; N 8.95.
Crystallization of a portion of hygroscopic amide 2a from benzene–acetonitrile without protection from
a moist air gave (N'-mesyl-N-methylprolinamidomethyl)dimethylsilyloxonium chloride (5a); mp 88-90°С
1
(C6H6–MeCN, 5:1). IR spectrum (KBr), , сm–1: 1612, 1509 (NCO), 1325 and 1143 (SO2). Н NMR spectrum
(CDCl3), δ, ppm: 0.51 (6H, s, Si(СН3)2); 1.89-2.06 and 2.06-2.23 (4H, m, 3,4-СH2); 2.84 (2Н, m, NCH2Si); 2.93
(3Н, s, СН3S); 3.15 (3H, s, СН3N); 3.45-3.53 (2H, m, 5-СH2); 4.79 (1H, m, 2-CH). 13С NMR spectrum (СDCl3), δ,
ppm: 6.7, 6.9 (Si(СН3)2); 24.9 (C-4); 30.8 (C-3); 37.6 (CH3N); 38.6 (CH3S); 41.1 (CH2Si); 48.2 (C-5); 56.9 (C-2);
172.1 (C=O). 29Si NMR spectrum (СDCl3), δ, ppm: -32.8. 29Si NMR spectrum CP/MAS, δ, ppm: -40.3. Found, %:
C 36.21; H 6.98; N 8.59. C10H23ClN2O4SSi. Calculated, %: С 36.30; Н 7.01; N 8.47.
N-(Dimethylchlorosilylmethyl)-N-methyl-N'-phenylsulfonyl-(S)-prolinamide ((S)-2b). A. A mixture
of compound (S)-1b (2.68 g, 10 mmol), (Me3Si)2NH (1.61 g, 10 mmol), and Me2Si(Cl)CH2Cl (2.68 g, 20 mmol)
in toluene (10 ml) was refluxed for 4 h and filtered while hot. The filtrate was cooled to room temperature. The
solvent was evaporated in vacuum. The oily residue was crystallized by trituration with ether (15 ml). The
crystals were washed with ether (3 ml) and dried., Yield 3.2 g (87%); mp 102-105 °С (C6H6–heptane, 1:1). IR
spectrum (KBr), , сm–1: 1606 (s), 1516 (w, NCO), 1344 (s) and 1155 (s, SO2).
B. A mixture of silacyclane (S)-4 (1.00 g, 5 mmol) and PhSO2Cl (0.88 g, 5 mmol) in absolute benzene
(10 ml) was stirred for 8 h. The solvent was removed in vacuum. The oily residue crystallized upon standing.
The crystals were washed with absolute ether. Yield 1.46 g (75%); mp 102-105°C (benzene). A mixed probe did
not give a depressed melting point. IR spectrum (solid, CHCl3), , сm–1: 1606 (s), 1516 (w, NCO), 1344 (s) and
1155 (s, SO2).
Crystallization of a part of hygroscopic amide (S)-2b from benzene–heptane mixture without protection
from a moist air gave (O→Si)-chelate (N-methyl-N'-phenylsulfonyl-(S)-prolinamidomethyl)dimethylsilyl-
25
oxonium chloride ((S)-5b); mp 83-85°С (C6H6–heptane, 1:1), [α]D -115.4° (c 0.57, MeCN). IR spectrum
(CHCl3), , сm–1: 3100–2900 (OH, CH), 1609, 1508 (NCO), 1330 and 1155 (SO2). 1Н NMR spectrum (CDCl3),
δ, ppm (J, Hz): 0.52 (6H, br. s, Si(СН3)2); 1.78-2.23 (4H, m, 3,4-СH2); 2.86 (2Н, s, CH2Si); 3.27 (3H, s, СН3N);
3
3.26–3.49 (2H, m, 5-СH2); 4.72 (1H, br. s, 2-CH); 7.48–7.73 (3H, m, Н Ar); 7.56 (2H, d, J = 7.7, Н Ar). 13С
NMR spectrum (СDCl3), δ, ppm: 6.3 (Si(СН3)2); 25.0 (C-4); 30.6 (C-3); 37.0 (СН3N); 44.7 (CH2Si); 48.3 (C-5);
55.5 (C-2); 127.2 (C-2,6 Ar); 128.3 (C-1 Ar); 129.2 (C-3,5 Ar); 133.1 (C-4 Ar). The carbon atom signal for the
C=O group is not observed due to extensive broadening. 29Si NMR spectrum (СDCl3), δ, ppm: -33.5. Found, %:
C 46.04; H 6.41; N 6.96. C15H25ClN2O4SSi. Calculated, %: С 45.85; Н 6.41; N 7.13.
N-(Dimethylchlorosilylmethyl)-N-methyl-N'-tosyl-(S)-prolinamide ((S)-2c). A. A mixture of
methylamide (S)-1c (2.80 g, 10 mmol), (Me3Si)2NH (1.61 g, 10 mmol), Me2Si(Cl)CH2Cl (2.86 g, 20 mmol) in
toluene (15 ml) was refluxed for 8 h. The hot reaction mixture was filtered and the filtrate was cooled to room
temperature. The solvent was evaporated in vacuum. The oily residue was recrystallized by stirring with ether.
The crystals were washed with ether (3 ml) and dried. Yield 3.4 g (88%); mp 100-102°С (C6H6). IR spectrum
1
(KBr), , сm–1: 1608, 1510 (NCO), 1347 and 1156 (SO2). Н NMR spectrum (C6D6), δ, ppm (J, Hz): 0.90 and
1578

0.91 (6H, two s, Si(СН3)2); 1.28-1.73 (4H, m, 3,4-СH2); 2.11 (3Н, s, СН3); 2.63 (3H, s, СН3N); 2.75 (2Н, q,
3
2J = 12.4, CH2Si); 3.17-3.28 (2H, m, 5-СH2); 4.45-4.49 (1H, m, 2-CH); 7.07 (2H, d, J = 8.1, Н Ar); 7.82 (2H,
3
13
d, J = 8.1, Н Ar). С NMR spectrum (С6D6), δ, ppm: 8.0 (Si(СН3)2); 21.6 (СН3С6Н4); 25.4 (C-4); 30.7 (C-3);
36.6 (СН3N); 45.7 (CH2Si); 48.8 (C-5); 56.0 (C-2); 128.0 (C-2,6 Ar); 130.4 (C-3,5 Ar); 136.7 (C-1 Ar); 144.4
(C-4 Ar); 174.7 (C=O). 29Si NMR spectrum (С6D6), δ, ppm: -36.8. Found, %: C 49.17; H 6.55; N 6.98.
C16H25ClN2O3SSi. Calculated, %: С 49.40; Н 6.48; N 7.20.
B. Me2Si(Cl)CH2Cl (1.43 g, 10 mmol) in benzene (5 ml) was added dropwise with stirring to
methylamide (S)-1c (2.80 g, 10 mmol) and Et3N (1.01 g, 10 mmol) in benzene. The reaction mixture was
refluxed for 3 h and then cooled to 20°C. The precipitate formed was filtered off and washed with ether (15 ml).
The solvent was evaporated in vacuum. The oily residue was crystallized upon stirring with ether. The crystals
were washed with ether (2 ml) and recrystallized from benzene. Yield 2.5 g (65%); mp 100–102°С. IR spectrum
(KBr), , сm–1: 1608, 1510 (NCO), 1347 and 1156 (SO2).
C. A mixture of silacyclane (S)-4 (1.00 g, 5 mmol) and p-toluenesulfonyl chloride (0.96 g. 5 mmol) in
absolute benzene (10 ml) was stirred for 8 h. The solvent was evaporated in vacuum. The oily residue was
crystallized by stirring in ether. The crystals were washed with absolute ether. Yield 1.6 g (81%). IR spectrum
(KBr), , сm–1: 1608, 1510 (NCO), 1347 and 1156 (SO2).
D. SOCl2 (0.178 g, 1.5 mmol) was added dropwise to a solution of disiloxane (S,S)-6c (0.720 g,
1.0 mmol) in benzene (5 ml) and stirred for 30 min. The reaction mixture was evaporated in vacuum. The oily
residue was crystallized upon stirring in ether. The crystals were washed with ether (1 ml) and dried Yield 0.65 g
(83%); mp 100-102°С (C6H6); mp of mixed probe 100-102°С.
Crystallization of crude chloride (S)-2c (0.78 g, 2 mmol) from o-xylene (3 ml) without protection from a
moist air gave 0.75 g (92%) (N-methyl-N'-tosyl-(S)-prolinamidomethyl)dimethylsilyloxonium chloride ((S)-5c);
mp 86-89°С (o-xylene), [α]D -55.1° (c 1.48, CHCl3). IR spectrum (CHCl3), , сm–1: 3000–2800 (ОН, CH),
25
1
1611, 1509 (NCO), 1351, 1158 (SO2). Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 0.50 (6H, s, Si(СН3)2);
1.76-1.98 and 2.04-2.21 (4H, m, 3,4-СH2); 2.45 (3Н, s, СН3); 2.87 (2Н, s, CH2Si); 3.27 (3H, s, СН3N);
3.36-3.50 (2H, m, 5-СH2); 4.66-4.77 (1H, m, 2-CH); 7.33 (2H, d, 3J = 8.5, Н Ar); 7.73 (2H, d, 3J = 8.5, H Ar).
13С NMR spectrum (СDCl3), δ, ppm: 5.0 (Si(СН3)2); 21.5 (СН3С6Н4); 25.0 (C-4); 30.6 (C-3); 37.0 (CH3N); 44.7
(CH2Si); 48.3 (C-5); 55.5 (C-2); 127.3 (C-2,6 Ar); 128.3 (C-1 Ar); 129.8 (C-3,5 Ar); 135.4 (C-4 Ar). The carbon
atom signal of the C=O group was not observed. 29Si NMR spectrum (СDCl3) δ, ppm: -34.0. 29Si NMR
spectrum CP/MAS, δ, ppm: -43.4. Found, %: C 47.93; H 6.65; N 6.44. C16H27ClN2O4SSi. Calculated, %:
С 47.22; Н 6.69; N 6.88.
N'-(4-Chlorophenylsulfonyl)-N-(dimethylchlorosilylmethyl)-N-methyl-(S)-prolinamide ((S)-2d). A
mixture of methylamide (S)-1d (3.03 g, 10 mmol), (Me3Si)2NH (1.61 g, 10 mmol), and Me2Si(Cl)CH2Cl
(2.86 g, 20 mmol) in toluene (15 ml) was refluxed for 5 h and filtered while hot. The filtrate was cooled to room
temperature and the solvent was removed in vacuum. The oily residue was crystallized by stirring in ether. The
crystals were filtered off, washed with ether (2 ml), and dried. Yield 3.3 g (80%); mp 89-93°C (C6H6–heptane,
1:1). IR spectrum (KBr), , сm–1: 1605, 1500 (NCO), 1316 and 1152 (SO2). Found, %: C 44.26; H 5.35; N 6.95;
S 7.94. C15H22Cl2N2O3SSi. Calculated, %: С 44.01; Н 5.42; N 6.84; S 7.83.
Crystallization of hygroscopic amide (S)-2d (0.82 g, 2 mmol) from 1:1 benzene–heptane mixture (3 ml)
without protection from a moist air gave 0.80 g (94%) (N-methyl-N'-chlorophenylsulfonyl-(S)-prolin-
amidomethyl)dimethylsilyloxonium chloride ((S)-5d); mp 126-128°С (C6H6–heptane, 1:1), [α]D25 -22.2° (c 1.01,
CHCl3). IR spectrum (KBr), , сm–1: 3000-2800 (OH, CH), 1610, 1501 (NCO), 1316 and 1152 (SO2). 1Н NMR
spectrum (CDCl3), δ, ppm (J, Hz): 0.50 (6H, s, Si(СН3)2); 1.76-1.95 and 2.00-2.20 (4H, m, 3,4 СH2); 2.90 (2Н,
3
s, CH2Si); 3.25 (3H, s, СН3N); 3.40-3.55 (2H, m, 5-СH2); 4.70 (1H, br. s, 2-CH); 7.45 (2H, d, J = 8.5, H Ar);
3
7.79 (2H, d, J = 8.5, H Ar). 13С NMR spectrum (СDCl3), δ, ppm: 3.9 (Si(СН3)2); 24.8 (C-4); 30.5 (C-3); 37.0
(CH3N); 43.2 (CH2Si); 48.2 (C-5); 55.8 (C-2); 128.5 (C-2,6 Ar); 129.4 (C-3,5 Ar); 136.6 (C-1 Ar); 139.4 (C-4
Ar); 173.7 (C=O). 29Si NMR spectrum (СDCl3) δ, ppm: -36.0. Found, %: C 42.28; H 5.54; N 6.30; S 7.41.
C15H24Cl2N2O4SSi. Calculated, %: С 42.15; Н 5.66; N 6.55; S 7.50.
1579

N'-(4-Bromophenylsulfonyl)-N-(dimethylchlorosilylmethyl)-N-methyl-(S)-prolinamde ((S)-2e). A
mixture of methylamide (S)-1e (3.47 g, 10 mmol), (Me3Si)2NH (1.61 g, 10 mmol), and Me2Si(Cl)CH2Cl
(2.86 g, 20 mmol) in toluene (15 ml) was refluxed for 3 h and filtered while hot to remove the precipitate
formed. The filtrate was cooled to room temperature. The crystalline precipitate was filtered off, washed with
ether (5 ml), and dried. Yield 3.85 g (85%); mp 127-129°С (C6H6). IR spectrum (CHCl3), , сm–1: 1605, 1572
(Ar), 1519 (NCO), 1344 and 1156 (SO2). Found, %: C 39.85; H 4.91; N 6.06; S 7.15. C15H22BrClN2O3SSi.
Calculated, %: С 39.70; Н 4.89; N 6.17; S 7.07.
Crystallization of hygroscopic amide (S)-2e (0.91 g, 2 mmol) from benzene (3 ml) without protection
from a moist air gave 0.9 g (95%) (N'-(4-bromophenylsulfonyl)-N-methyl-(S)-prolinamidomethyl)dimethyl-
silyloxonium chloride (S)-5e; mp 95-97°С (C6H6), [α]D -12.4° (c 3.25, CHCl3). IR spectrum (KBr), , сm–1:
25
3000-2800 (OH, CH), 1609, 1571 (Ar), 1510 (NCO), 1344 and 1156 (SO2). 1Н NMR spectrum (CDCl3), δ, ppm
2
(J, Hz): 0.52, 0.58 (6H, two s, Si(СН3)2); 1.80-1.90 and 2.10-2.25 (4H, m, 3,4-СH2); 2.82 (1Н, d, J = 14.8) and
2.92 (2Н, d, 2J = 14.8, CH2Si); 3.27 (3H, s, СН3N); 3.38–3.49 (2H, m, 5-СH2); 4.78 (1H, br. s, 2-CH); 7.68 (2H,
3
3
13
d, J = 8.3, Н Ar); 7.78 (2H, d, J = 8.3, H Ar). С NMR spectrum (СDCl3), δ, ppm: 7.8 (br. s, Si(СН3)2); 25.0
(C-4); 30.6 (C-3); 37.8 (br. s, CH3N); 40.5 (br. s, CH2Si); 48.2 (C-5); 55.5 (C-2); 128.8 (C-2,6 Ar); 132.4 (C-3,5
Ar). The signals for C-1,4 Ar and the C=O group are not observed due to broadening. 29Si NMR spectrum
(СDCl3), δ, ppm: -32.8. Found, %: C 38.44; H 5.19; N 6.07. C15H24BrClN2O4SSi. Calculated, %: С 38.18;
Н 5.13; N 5.94.
N-(Dimethylchlorosilylmethyl)-N-methyl-N'-(4-nitrophenylsulfonyl)prolinamide (2f). A. A mixture
of methylamide 1f (3.12 g, 10 mmol), (Me3Si)2NH (1.61 g, 10 mmol), and Me2Si(Cl)CH2Cl (2.86 g, 20 mmol)
in toluene (15 ml) was refluxed for 2 h. The filtrate was cooled to room temperature. The crystalline precipitate
was filtered off, washed with ether (3 ml), and dried. Yield 3.99 g (95%); mp 84-88°С. IR spectrum (KBr), , сm–
1: 1606 (NCO), 1525 (NO2, NCO), 1349 (NO2, SO2), 1160 (SO2).
B. SOCl2 (0.30 g, 2.5 mmol) was added dropwise with stirring to a solution of disiloxane 6f (1.57 g,
2.0 mmol) in benzene (10 ml). The precipitate formed was filtered off and washed with absolute ether. Yield
1.5 g (90%); mp 84-88°C; mp of mixed probe 84-88°С. 29Si NMR spectrum CP/MAS, δ, ppm: -43.3.
Crystallization of crude chloride 2f (0.84 g, 2 mmol) from acetonitrile (3 ml) without protection from a
moist air gave 0.91 g (95%) the acetonitrile monosolvate of [N-methyl-N'-(4-nitrophenylsulfonyl)prolin-
amidomethyl]dimethylsilyloxonium chloride (5f); mp 98-102°С (MeCN). IR spectrum (KBr), , сm–1: 3000-2800
1
(OH, CH), 2260 (СN, MeCN), 1609 (NCO), 1527 (NO2, NCO), 1348 (NO2, SO2), 1156 (SO2). Н NMR
spectrum (СD3CN), δ, ppm (J, Hz): 0.42 (6H, s, Si(СН3)2); 1.68–2.15 (4H, m, 3,4-СH2); 2.80 (2Н, s, CH2Si);
3
3.18 (3H, s, СН3N); 3.33-3.49 (2H, m, 5-СH2); 4.70 (1H, m, 2-CH); 8.05 (2H, d, J = 8.8, H Ar); 8.37 (2H, d,
3J = 8.8, H Ar). 13С NMR spectrum (СD3CN), δ, ppm: 1.4 (Si(СН3)2); 25.5 (C-4); 31.4 (C-3); 37.5 (СН3N); 45.2
(CH2Si); 49.7 (C-5); 57.5 (C-2); 125.6 (C-2,6 Ar); 128.2 (C-3,5 Ar); 129.6 (C-1 Ar); 137.5 (C-4 Ar); 171.2
(C=O). 29Si NMR spectrum (СD3CN), δ, ppm: -36.8. 29Si NMR spectrum CP/MAS, δ, ppm: -42.2. Found, %:
C 42.57; H 5.28; N 11.56. C17H27ClN4O6SSi. Calculated, %: С 42.62; Н 5.68; N 11.70.
1,1,3,3-Tetramethyl-1,3-bis(N-methyl-N'-organosulfonylprolinamidomethyl)-1,3-disiloxanes 6a-f
(General Method). A solution of NaHCO3 (1.26 g, 15 mmol) in water (10 ml) was added with stirring to
chloride 2 (10 mmol) in chloroform (10 ml) and stirred for 24 h. The organic layer was separated and the
aqueous layer was extracted with chloroform (10 ml). The organic extract was evaporated in vacuum. The
residue was crystallized by trituration with heptane (15 ml). The crystals were separated and dried.
1,3-Bis(N'-mesyl-N-methylprolinamidomethyl)-1,1,3,3-tetramethyl-1,3-disiloxane (6a). Yield 2.65 g
1
(93%); mp 110-114°С (hexane). IR spectrum (KBr), , сm–1: 1640 (NCO), 1311 and 1145 (SO2). Н NMR
spectrum (CDCl3), δ, ppm: 0.00-0.34 (12H, m, 2Si(СН3)2); 1.77-2.38 (8H, m, two 3,4-СH2); 2.88 (4Н, s,
2CH2Si); 2.99 (6H, s, 2СН3S); 3.06 (6H, s, 2СН3N); 3.38-3.67 (4H, m, two 5-СH2); 4.73–4.92 (2H, m, 2H-2).
13С NMR spectrum (СDCl3), δ, ppm: 0.6 (Si(СН3)2); 24.8 (C-4); 30.8 (C-3); 37.7 (СН3N); 39.2 (СН3S); 41.9
(CH2Si); 47.8 (C-5); 58.9 (C-2); 170.6 (C=O). 29Si NMR spectrum (СDCl3) δ, ppm: 4.8. Found, %: C 42.21;
H 7.32; N 9.99. C20H42N4O7S2Si2. Calculated, %: С 42.08; Н 7.42; N 9.81.
1580

1,1,3,3-Tetramethyl-1,3-bis(N-methyl-N'-phenylsulfonyl-(S)-prolinamidomethyl)-1,3-disiloxane
((S,S)-6b). Yield 3.3 g (95%), oil, nD 1.5077, [α]D25 -39.3° (c 1.57, CHCl3). IR spectrum (СHCl3), , сm–1:
20
1642 (NCO), 1571 and 1470 (Ar), 1348 and 1155 (SO2). 1Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 0.10-0.30
(12H, m, 2Si(СН3)2); 1.77-2.18 (8H, m, two 3,4-СH2); 2.78 (4Н, s, 2CH2Si); 3.06 (6H, s, 2СН3N); 3.38-3.47
(4H, m, two 5-СH2); 4.80-4.89 (2H, m, two 2-CH) 7.55 (4H, t, 3J = 7.7, Н Ar); 7.62 (2H, t, 3J = 7.7, Н Ar); 7.67
3
(4H, d, J = 7.7, Н Ar). 13С NMR spectrum (СDCl3), δ, ppm: 0.4 (Si(СН3)2); 24.8 (C-4); 30.8 (C-3); 37.7
(СН3N); 41.9 (CH2Si); 48.2 (C-5); 57.5 (C-2); 127.6 (C-2,6 Ar); 129.6 (C-3,5 Ar); 132.5 (C-1 Ar); 139.1 (C-4
Ar); 170.3 (C=O). 29Si NMR spectrum (СDCl3) δ, ppm: 4.8.
1,1,3,3-Tetramethyl-1,3-Bis(N-methyl-N'-tosyl-(S)-prolinamidomethyl)-1,3-disiloxane ((S,S)-6c).
Yield 3.24 g (90%); mp 125-126°С (hexane), [α]D -58.2° (c 2.16, CHCl3). IR spectrum (СHCl3), , сm–1: 1640
25
(NCO), 1600 and 1460 (Ar), 1336 and 1164 (SO2). 1Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 0.05-0.31 (12H, m,
2Si(СН3)2); 1.63-2.19 (8H, m, two 3,4-СH2); 2.41 (6Н, s, 2СН3С6Н4); 2.81-2.98 (4Н, m, 2CH2Si); 3.16 (6H, s,
3
2СН3N); 3.32-3.54 (4H, m, two 5-СH2); 4.79 (2H, br. s, two 2-CH); 7.28 (4H, d, J = 7.6, Н Ar); 7.78 (4H, d,
3J = 7.6, Н Ar). 13С NMR spectrum (СDCl3), δ, ppm: 0.4 (Si(СН3)2); 21.6 (СН3С6Н4); 25.0 (C-4); 30.8 (C-3); 37.9
(СН3N); 42.0 (CH2Si); 48.4 (C-5); 57.5 (C-2); 127.6 (C-2,6 Ar); 129.6 (C-3,5 Ar); 136.2 (C-1 Ar); 143.4 (C-4 Ar);
170.3 (C=O). 29Si NMR spectrum (СDCl3) δ, ppm: 4.8. Found, %: C 53.01; H 7.19; N 7.60; S 8.75.
C32H50N4O7S2Si2. Calculated, %: C 53.15; H 6.97; N 7.75; S 8.87.
1,3-Bis[N'-(4-chlorophenylsulfonyl)-N-methyl-(S)-prolinamidomethyl]-1,1,3,3-tetramethyl-1,3-disil-
25
oxane ((S,S)-6d). Yield 3.55 g (93%); mp 120-124°С (heptane), [α]D -10.6° (c 3.41, CHCl3). IR spectrum
1
(СHCl3), , сm–1: 1649 and 1585 (NCO), 1470 (Ar), 1336 and 1164 (SO2). Н NMR spectrum (CDCl3), δ,
ppm (J, Hz): 0.10-0.25 (12H, m, 2Si(СН3)2); 1.79–2.19 (8H, m, two 3,4-СH2); 2.82–2.90 (4Н, m, 2CH2Si); 3.12
3
(6H, s, 2СН3N); 3.32-3.48 (4H, m, two 5-СH2); 4.84 (2H, br. s, two 2-CH); 7.44 (4H, d, J = 7.6, Н Ar); 7.85
3
(4H, d, J = 7.6, Н Ar). 13С NMR spectrum (СDCl3), δ, ppm: 0.5 (Si(СН3)2); 25.0 (C-4); 30.7 (C-3); 37.8
(СН3N); 41.9 (CH2Si); 48.1 (C-5); 57.8 (C-2); 129.0 (C-2,3,5,6 Ar); 137.9 (C-1 Ar); 139.0 (C-4 Ar); 170.0
(C=O). 29Si NMR spectrum (СDCl3) δ, ppm: 4.8. Found, %: C 47.28; H 5.93; N 7.47. C30H44Cl2N4O7S2Si2.
Calculated, %: С 47.17; Н 5.81; N 7.33.
1,3-Bis[N'-(4-bromophenylsulfonyl)-N-methyl-(S)-prolinamidomethyl]-1,1,3,3-tetramethyl-1,3-disil-
25
oxane ((S,S)-6e). Yield 4 g (94%); mp 117-118°С (hexane), [α]D +0.45° (c 2.66, CHCl3). IR spectrum
1
(СHCl3), , сm–1: 1643 (NCO), 1573 (NCO), 1470 (Ar), 1348 and 1155 (SO2). Н NMR spectrum (CDCl3), δ,
ppm (J, Hz): 0.15-0.30 (12H, m, 2Si(СН3)2); 1.81-2.19 (8H, m, two 3,4-СH2); 2.82-2.94 (4Н, m, 2CH2Si); 3.18
3
(6H, s, 2СН3N); 3.35-3.48 (4H, m, two 5-СH2); 4.88 (2H, br. s, two 2-CH); 7.64 (4H, d, J = 7.6, Н Ar); 7.82
3
(4H, d, J= 7.6, Н Ar). 13С NMR spectrum (СDCl3), δ, ppm: 0.5 (Si(СН3)2); 24.8 (C-4); 30.9 (C-3); 37.8
(СН3N); 42.2 (CH2Si); 48.1 (C-5); 57.8 (C-2); 127.5 (C-1 Ar); 129.1 and 132.1 (C-2,3,5,6 Ar); 138.5 (C-4 Ar);
170.0 (C=O). 29Si NMR spectrum (СDCl3) δ, ppm: 3.9. Found, %: C 42.05; H 5.15; N 6.41.
C30H44Br2N4O7S2Si2. Calculated, %: С 42.25; Н 5.20; N 6.57.
1,1,3,3-Tetramethyl-1,3-bis[N-methyl-N'-(4-nitrophenylsulfonyl)propylamidomethyl]-1,3-disiloxane
(6f). Yield 3.8 g (96%); mp 141-146°С (heptane). IR spectrum (KBr), , сm–1: 1647 (NCO), 1525 (NO2), 1350
(NO2, SO2), 1160 (SO2). 1Н NMR spectrum (CDCl3), δ, ppm (J, Hz): 0.03-0.33 (12H, m, 2Si(СН3)2); 1.78-2.35 (8H,
m, two 3,4-СH2); 2.76-2.91 (4Н, m, 2CH2Si); 3.13 (6H, s, 2СН3N); 3.29-3.45 and 3.49-3.67 (4H, m, two 5-СH2);
4.94 (2H, br. s, two 2-CH); 8.12 (4H, d, 3J = 4.2, Н Ar); 8.34 (4H, d, 3J = 4.2, Н Ar). 13С NMR spectrum (СDCl3), δ,
ppm: 0.6 (Si(СН3)2); 25.0 (C-4); 30.9 (C-3); 37.8 (СН3N); 41.9 (CH2Si); 48.2 (C-5); 58.5 (C-2); 124.0 (C-2,6 Ar);
128.9 (C-3,5 Ar); 145.5 (C-1Ar); 150.0 (C-4Ar); 170.0 (C=O). 29Si NMR spectrum (СDCl3) δ, ppm: 4.8.
2,2,4-Trimethyl-1,4-diaza-2-silabicyclo[4.3.0]nonan-5-one ((S)-4). A. Me2Si(Cl)CH2Cl (15.7 g,
110 mmol) in absolute ether (10 ml) was added dropwise to a mixture of absolute ether (50 ml), methylamide
(S)-3 (12.8 g, 100 mmol) and abs. Et3N (11.0 g, 110 mmol) and refluxed for 4 h. The precipitate formed was
filtered off and the residue was fractionated. Yield 10 g (50%), a thick oil; bp 138-140°С (12 mm Hg). IR
1
spectrum (CHCl3), , сm–1: 1641 (NCO). Н NMR spectrum (CDCl3), δ, ppm: 0.00-0.30 (6H, s, Si(СН3)2);
1.56-2.56 (4H, m, 7,8-СH2); 2.75 (2Н, s, CH2Si); 2.98 (3H, s, СН3N); 3.26-3.38 (2H, m, 9-СH2); 3.55–3.65 (1H,
1581

m, H-6). 13С NMR spectrum (СDCl3), δ, ppm: 0.5 (Si(СН3)2); 26.5 (C-8); 30.8 (C-7); 37.0 (СН3N); 41.6 (C-3);
47.9 (C-9); 58.1 (C-6); 173.2 (C=O). 29Si NMR spectrum (СDCl3) δ, ppm: 4.3. Found, %: C 54.20; H 9.22;
N 14.00. C9H18N2OSi. Calculated, %: С 54.50; Н 9.15; N 14.12.
B. A mixture of methylamide (S)-3 (12.80 g, 100 mmol) and (Me3Si)2NH (24.15 g, 150 mmol) was
refluxed for 6 h. Then, Me2Si(Cl)CH2Cl (15.73 g, 110 mmol) and (Me3Si)2NH (12.07 g, 75 mmol) were added
and the mixture was refluxed for an additional 6 h. After cooling to room temperature, the mixture was
25
evaporated in vacuum and the residue was fractionated. Yield 8.0 g (40%); bp 138–142°С (12 mm Hg), [α]D
-50.6° (c 4.57, CH2Cl2). The spectral data for the samples of (S)-4 obtained by both procedures were identical.
X-ray Structural Analysis of 2a-f, 5a,s,d,f. Monocrystals for X-ray structural analysis were obtained
by crystallization of samples of 2a and 5f from acetonitrile, (S)-2b, (S)-2d, and (S)-5d from 5:1 benzene-heptane
mixture, silyl chlorides (S)-2c, and (S)-2e from benzene, silyloxonium chloride 5a from 5:1
benzene−acetonitrile mixture, and (S)-5c from o-xylene. In the case of silyl chloride 2f, crystals precipitated
directly from the reaction mixture were used.
The major crystallographic data and refinement results for the 10 complexes analyzed are given in
Table 4. The structures were solved by the direct method and refined anisotropically by the full-matrix method
of least squares for the non-hydrogen atoms. The hydrogen atoms of the alkyl and aryl fragments were
calculated from geometrical considerations and included in the refinement with equivalent thermal parameters
dependent on the attached carbon atoms (Ueq(H) = 1.2Ueq(C), 1.5Ueq(CMe)). The hydrogen atoms in the oxonium
fragments were revealed in the electron density Fourier difference maps. Their thermal parameters were refined
analogously (Ueq(H) = 1.5Ueq(O)). All the calculations were carried out using the SHELTX-97 V.5.10 software
package [37]. The atomic coordinates and their temperature parameters for compounds 2a-g, 5a,s,d,f were
deposited in the Cambridge Crystallographic Data Center (CCDC 833653-833662).
This work was carried out with the financial support of the Russian Foundation for Fundamental
Investigations (projects Nos. 09-03-00669, 10-03-00824, and 11-03-00655) as part of the activities of the
Russian State Medical University Scientific Educational Center.
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